Office Capacity Limits

A Guide By Colin Stuart

How many people can you fit in an office? What are the legal office capacity limits? How many toilets should I have in an office? What is best practice? This guide is to help you answer those questions, to try to demystify the current rules and regulations and give you practical advice and guidance.

As a business it is important to make best use of your assets. Office space is often wasted and with the cost of the provision of office space reaching anything up to £23,500 per desks in parts of London (Lambert Smith Hampton TOCS Report 2018) it is tempting to try to “sweat the asset” and make the most efficient use of your office space. It is important however, when undertaking office space planning, that you take proper notice of the law and how it relates to the provision of office space and the rights of the workers in that office.

What are the Office Capacity Limits?

One of the key areas of law that affects the workplace is in the limits the law places on the number of people you can fit into an office. There are four primary limiting factors (often called the statutory office capacity limits or statutory capacity) you need to consider when assessing the capacity of your offices and how many people you can fit in:

Means of escape – There is a limit to the number of people you are allowed to have on a floor which is governed by the Building Regulations 2010 and Part B of the approved documents (Fire Safety). The capacity limits depend upon your specific building, the fire escape strategy designed for that building and a number of other factors including fire escape door widths, width and location of escape staircases, distance of travel to those staircases. Your landlord or building developer should to provide you with the fire escape strategy and the specific occupancy limits imposed per floor. If these are unavailable, then specialist help should be obtained.

Space or Volume – Regulation 10 of the Workplace (Health, Safety and Welfare) Regulations states that “Every room where persons work shall have sufficient floor area, height and unoccupied space for purposes of health, safety and welfare.” But again, what does this actually mean. Luckily the approved code of practice has guidance for regulation 10 as well. It states that “Workrooms should have enough free space to allow people to get to and from workstations and to move within the room, with ease”. It goes on to specify that “the total volume of the room, when empty, divided by the number of people normally working in it should be at least 11 cubic metres”. In making this calculation a room or part of a room which is more than 3.0m high should be counted as 3.0m high. The figure of 11 cubic metres per person is a minimum and may be insufficient if, for example, much of the room is taken up by furniture etc.”

Ventilation or Fresh Air – for the provision of general ventilation in offices the Health and Safety Executive (HSE) recommendations state: “All workplaces need an adequate supply of fresh air. This can be natural ventilation, from doors, windows etc or controlled, where air is supplied and/or removed by a powered fan”. Further CIBSE recommends that “A minimum fresh air requirement of 8 to 10 l/s per person typically adopted in mechanically ventilated spaces”. Fresh air requirements for naturally ventilated spaces are treated differently and as with fire capacity, HVAC design a complex area and depends on a number of factors and where not already known then specialist advice should be obtained.

Density and Key Ratios

Even if you are in compliance with the office capacity statutory limits above there are other considerations which will limit the number of people you can fit on your office floor.

Desk Density – there is a physical limit to the number of desks you can fit into an office. It depends upon the desk size, the amount of storage you have in your office (see our article on storage in an agile environment), and the other facilities you wish to include such as ad-hoc meeting space, quiet rooms, meeting rooms etc. If you are going for a very dense layout (often called a “max-pack” layout) you need to ensure you are maintaining adequate widths between desks for means of escape and to allow for access by wheelchair users. See our guide on office desk sizing and spacing for further information.

Best practice – as well as considering your max pack limits, to get your workplace to not just be efficient but also effective in how it supports you organisation and the staff working within, it is vital you also consider the environment you are trying to create. A layout densely packed with desks, especially if a desk sharing policy has also been used will create a very “battery chicken” like feel to your office, potentially lowering staff morale and productivity and impacting staff retention – people will vote with their feet! An effective workplace is designed to support the business and with consideration for the people working within the space. You should consider the tasks and activities they are performing and where these are done best – what we like to call “People Centric Design”. Factoring in alternative work areas (often called agile work settings) such as collaboration space, quiet areas / rooms, meeting booths and breakout areas may not be as efficient but creates a much more effective environment that supports the work done within. Its about getting the balance right. For further information on the benefits of agile working please see article “Agile Working, The Case for Change”

Space Efficiency Ratios – one of the ways you can benchmark your office is to calculate your space efficiency ratios, such as space per person and space per workstation. These are normally calculated using the Net Internal Area (NIA) of your office, which excludes core space such as staircases, lift lobbies, plant rooms and main reception areas. It is a good measure of office efficiency as it includes all space comprising the usable office area such as desks, meeting rooms, alternative work / collaboration areas and circulation space. The British Council for Offices Specification recommends 8 – 13 m2 per person. Recent BCO research however found an average of 9.6 m2 per person and concluded that minimum of 6 m2 per person should be provided. For public sector space, current British Government space targets are 8 m2 per FTE (full time equivalent member of staff) however the government publishes an annual survey of all of its property (the State of the Estate report) and it found that the average was 9.9 m2.

Disclaimer: This article is intended as a guide only, to give you general information and a general understanding of the topics. We strive to provide to you accurate information that can help you learn more about the topics covered on the website, but we cannot take personal or legal responsibility for your use of this information.We do not warrant the accuracy of any of the information contained in this article or elsewhere on our website and you should check the latest official publications and seek the advice of a suitably qualified professional.